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Abstract. Identifying the causes for historical sea-level changes in coastal tide-gauge records is important for constraining oceanographic, geologic, and climatic processes. The Río de la Plata estuary in South America features the longest tide-gauge records in the South Atlantic. Despite the relevance of these data for large-scale circulation and climate studies, the mechanisms underlying relative sea-level changes in this region during the past century have not been firmly established. I study annual data from tide gauges in the Río de la Plata and stream gauges along the Río Paraná and Río Uruguay to establish relationships between river streamflow and sea level over 1931–2014. Regression analysis suggests that streamflow explains 59 %±17 % of the total sea-level variance at Buenos Aires, Argentina, and 28 %±21 % at Montevideo, Uruguay (95 % confidence intervals). A long-term streamflow increase effected sea-level trends of 0.71±0.35 mm yr−1 at Buenos Aires and 0.48±0.38 mm yr−1 at Montevideo. More generally, sea level at Buenos Aires and Montevideo respectively rises by (7.3±1.8)×10-6 m and (4.7±2.6)×10-6 m per 1 m3 s−1 streamflow increase. These observational results are consistent with simple theories for the coastal sea-level response to streamflow forcing, suggesting a causal relationship between streamflow and sea level mediated by ocean dynamics. Findings advance understanding of local, regional, and global sea-level changes; clarify sea-level physics; inform future projections of coastal sea level and the interpretation of satellite data and proxy reconstructions; and highlight future research directions. Specifically, local and regional river effects should be accounted for in basin-scale and global mean sea-level budgets as well as reconstructions based on sparse tide-gauge records.
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This content will become publicly available on June 2, 2027
Variable contributions of vertical land motion to sea-level change inferred at tide gauges
Vertical land motion is a key component of relative sea-level changes in coastal areas. Rates of vertical land motion can vary temporally owing to anthropogenic and natural processes. Yet, such nonlinear behaviour has not been fully accounted for in twentieth-century sea-level budgets or projections because long-term observations at relevant spatial scales are scarce. Here we infer vertical land motion at a global set of tide gauge stations by comparing their records with a probabilistic reconstruction of climate-related sea level (1900–2021) that integrates model-based estimates of sterodynamic, barystatic and inverse-barometer contributions. Differences between climate-related sea-level and tide gauge records primarily reflect vertical land motion and reveal previously unreported temporal variations linked to subsurface fluid withdrawal, as well as seismic and volcanic processes. We show that decadal fluctuations in regional relative sea-level trends can exceed those driven by climate-related processes by an order of magnitude. Consequently, vertical land motion projections based on linear extrapolations introduce systematic median sea-level projection errors of typically up to 7.6 mm yr−1 at sites influenced by seismic or volcanic activity and 5.6 mm yr−1 at the other sites. Our time-varying vertical land motion estimates constrain geophysical models of anthropogenic and volcano-tectonic crustal processes and pave the way for more robust sea-level projections at tide gauges.
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- PAR ID:
- 10694054
- Publisher / Repository:
- Springer Nature
- Date Published:
- Journal Name:
- Nature Geoscience
- ISSN:
- 1752-0894
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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